Xiao-Feng, Could you please revert the last patch2 and re-open JIRA - i've found the real issue and want to post it there. (See my comment in JIRA).
Thanks, Mikhail On 5/24/07, Xiao-Feng Li (JIRA) <[EMAIL PROTECTED]> wrote:
[ https://issues.apache.org/jira/browse/HARMONY-3883?page=com.atlassian.jira.plugin.system.issuetabpanels:comment-tabpanel#action_12498449] Xiao-Feng Li commented on HARMONY-3883: --------------------------------------- Mike, I will commit your patch2, and close this issue, while opening another JIRA for the java.lang.ThreadGroup.java issue. The goal is to solve this java.lang.ThreadTest failure finally. Thanks, xiaofeng -- http://xiao-feng.blogspot.com > [classlib]WeakHashMap.keySet().toArray() intermittently throws NoSuchElementException in java.lang.ThreadTest of DRLVM kernel test > ---------------------------------------------------------------------------------------------------------------------------------- > > Key: HARMONY-3883 > URL: https://issues.apache.org/jira/browse/HARMONY-3883 > Project: Harmony > Issue Type: Bug > Components: Classlib > Environment: win/linux 32/64 > Reporter: Li-Gang Wang > Attachments: H-3883.patch, H-3883_add_alt1.patch, H-3883_add_alt2.patch, WeakHashmapTest.java > > > I found there is a design bug in WeakHashMap.keySet().toArray() . > WeakHashMap.keySet().toArray() inherits AbstractCollection.toArray(). Its implementation is as follows: > public Object[] toArray() { > int size = size(), index = 0; > Iterator<?> it = iterator(); > Object[] array = new Object[size]; > while (index < size) { > array[index++] = it.next(); > } > return array; > } > After assigning 'size()' to 'size', the 'while' loop expects 'size' elements in the iterator 'it'. But actually GC might happen and clear some weak keys of the WeakHashMap instance in the meantime. The iterator will skip the cleared weak keys in 'it.hasNext()' called by 'it.next()', so the actual number of the elements in 'it' is smaller than 'size'. When 'it' runs out its elements, 'it.next()' will throw a NoSuchElementException. Parts of HashIterator implementation in WeakHashMap is as follows: > public boolean hasNext() { > if (nextEntry != null) { > return true; > } > while (true) { > if (nextEntry == null) { > while (position < elementData.length) { > if ((nextEntry = elementData[position++]) != null) { > break; > } > } > if (nextEntry == null) { > return false; > } > } > // ensure key of next entry is not gc'ed > nextKey = nextEntry.get(); > if (nextKey != null || nextEntry.isNull) { > return true; > } > nextEntry = nextEntry.next; > } > } > public R next() { > if (expectedModCount == modCount) { > if (hasNext()) { > currentEntry = nextEntry; > nextEntry = currentEntry.next; > R result = type.get(currentEntry); > // free the key > nextKey = null; > return result; > } > throw new NoSuchElementException(); > } > throw new ConcurrentModificationException(); > } > I suspect the intermittent failure in java.lang.ThreadTest may disappear if this bug is fixed. -- This message is automatically generated by JIRA. - You can reply to this email to add a comment to the issue online.
